VACUUM LINE MODIFICATION ON BASE MODEL M1

I try and make things as simple and direct as I can. KISS (Keep It Simple, Stupid)
is a method I agree with.

One day, my 1990 Miata, "GRACIE", started to run rough, and it seemed
like a vacuum leak. Well, it was but not easy to find. At the rear of the intake
manifold at the firewall is a 6mm nipple that is used for the Automatic Transmission.
Mazda simply caps this off if you have a 5-Speed. In this case, the heat had
caused the cap to fail.

I
never wanted this to happen again, so I took a long M6 bolt, cut the threads
off, and left about 1/2" of shank. I chucked this in a 3/8" drill
and used it to grind the head of the bolt smooth like a rivet. I then put a
thin coat of non-hardening gasket cement on it. While it was setting up, I took
a small ViseGrip Plier and pulled out the nipple. The fabricated plug was then
inserted into the hole, a nice snug fit. A simple fix!

But as I was about to close the hood for a quick run around the block, topless
of course, there was another capped vacuum nipple staring me in the face, right
on top of the intake manifold at the throttle body. This is used on cars with
Cruise Control. Also the way the other nipple pointed, the vacuum line ran around
the intake manifold, which absorbs heat and can lead to cracking and failure.

So, I retrieved my trusty ViseGrip, pulled the unused nipple, and pointed the
other nipple toward the throttle cable bracket. I then modified a 3/8"
conduit bracket to be snug on the vacuum line and rerouted the line. I had a
small collection of rivets, and found one which fit the hole for the nipple
perfectly! This is a 3/16" x 3/8" piece which cost me $.06 at the
hardware only1 week previous.

Not only does this simplify things, it looks good doing it! Now, about driving
with the top down...